Malignant gliomas represent the single most costly and morbid neoplasm per capita. During the previously funded nine years, this Program Project has evaluated a pipeline of cellular and HSV oncolytic viral therapies for this tumor. We have remained focused on these themes under Dr. Hochberg. Our productivity includes the development of pro-drug activation enzymes, oncolytic virus, tumor tracking using neural precursor cells and unique molecular imaging (e.g. MION) approaches demonstrated by collaborative and high impact publications. Three Projects and three Cores are united in collaboration with GLP/GMPproduction facilities of Dr. Glorioso, as a resource for the brain-tumor consortium (NABTT), to explore gene therapy for glioblastomas. Prior funding has set the stage for NGVL/Quick Trial applications in support of three Phase I human trials utilizing the oncolytic virus, MGH2. We continue our commitment to translational research by concentrating upon these biologic therapies, including potential modulation of resistance to oncolytic HSV and the development of novel imaging tools and gene delivery modalities. Project 1 (Chiocca) will determine mechanisms of the host response to the oncolytic virus and how this host response can be modulated to provide more efficient tumor killing . Project 3 (Breakefield/Carter/Sena-Esteves) will focus on enhancing MGH2 therapy by targeting infection to tumor cells and coupling it with HSV/AAV amplicon vectors encoding therapeutic proteins. They will also use AAV vectors, neuroprecursor cells (NPCs) and chimeric lymphocytes to extend the therapeutic field in the brain. Project 2 (Weissleder) provides the 'glue'for other projects by developing sensitive peptide labels which can be used to image therapeutic NPC and T cells, as well as oncolytic viruses in glial tumors. These novel imaging modalities will provide correlations with the biologic therapies explored in Projects 1 and 3. Clinical Core B (Krisky/Glorioso) will pilot the GLP and GMP production of MGH-2 and HSV amplicon vectors. The MGH2 GMP vector (supported by NGVL funding) will be offered to CTEP for Phase II NABTT trials. Tissue culture, murine and molecular analyses, as well as study and publication design are supported by statistical oversight in Core A (Finkelstein), as well as by histologic, molecular pathologic and immunocytochemical evalutions of brain tumor tissue (Core C, Louis). This program aims to answer hypotheses regarding key concerns underlying the conduct of future gene therapy trials for patients afflicted with brain tumors. In addition it offers, during five years of funding, the realistic goal of provision to human trials of improved oncolytic HSV vectors paradigms, targeted T cells and novel MRI imaging agents.